ffmpeg tile command: ordering frames top to bottom rather than left to right

Question

By default, the tile command builds the output one row at a time, from left to right. I would like instead for my output to be built in columns, top to bottom.

That is, for a 4x4 tiling, the tile command by default arranges the frames like so:

    1  2  3  4
    5  6  7  8
    8  10 11 12
    13 14 15 16

Whereas I would like for them to be arranged like so:

    1  5  9  13
    2  6  10 14
    3  7  11 15
    4  8  12 16

What is the easiest way to make this happen?

Answer 1

You can't change the behaviour of the tile filter, but you can adjust your inputs before and after to get the desired result.

ffmpeg -i input -vf hflip,transpose=cclock,tile=4x4,transpose=clock,hflip out.png

Note that the layout supplied to tile is transposed, so if you want the final result to be 6x4, tile should be given 4x6.